Study on the Process of Phosphogypsum Floatation Coupled with Acid Leaching for Impurity Removal and Whitening
Phosphogypsum,a bulk solid waste generated from the wet phosphoric acid process,is primarily disposed of through centralized stockpiling,which poses significant environmental risks.This study investigates the flotation and acid leaching conditions for phosphogypsum sourced from a phosphate fertilizer producer in Hubei,China.Optimal results were achieved under the following conditions:dodecylamine dosage of 200 g/t,slurry pH of 2.0,sulfuric acid concentration of 5%,liquid-solid ratio of 5:1,leaching time of 2 hours,and temperature of 35℃.The treated phosphogypsum exhibited a whiteness of over 70%,a CaSO4·2H2O purity exceeding 97%,and reduced soluble phosphorus and fluorine contents to 0.098%and 0.052%,respectively.FT-IR spectra,zeta potential,and surface tension analyses revealed that dodecylamine interacts with phosphogypsum surfaces through hydrogen bonding and physical adsorption.Additionally,the flotation process significantly decreased the silicon dioxide content in the concentrate.This method demonstrates simplicity,strong applicability,and potential to provide high-quality raw materials for the value-added utilization of phosphogypsum.
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